RFR: Fix concurrent partial handling of ShenandoahGCSession

[Zhengyu Gu]

Look good to me.

-Zhengyu

On 10/11/2017 01:54 PM, Aleksey Shipilev wrote:
> http://cr.openjdk.java.net/~shade/shenandoah/concpartial-session/webrev.01
> 
> ShenandoahGCSession is supposed to be called for the entire cycle, not the individual phases. The
> patch fixes this, and also moves the timers closer to VM op, where all other timers are done.
> 
> Testing: hotspot_gc_shenandoah
> 
> Thanks,
> -Aleksey
>